void init    (double* u, double* ut, double* dx, double* dt, int* N_step, int* N_diag);
void evolve  (double* u, double* ut, double dx, double dt);
void diagnose(double* u, double* ut, double dx, double dt);

int main(){
    int N_step, N_diag;
    double *u, *ut, dx, dt;
    init(u,ut,&dx,&dt,&N_step,&N_diag);
    for(int step=0; step<step_N; step++){
	evolve(u,ut,dx,dt);
	if(step%diag_step==0)
	    diagnose(u,ut,dx,dt);
    }
    return 0;
}


